This disclosure relates generally to computer storage management. More particularly, it relates to reclaiming computer storage volumes.
In a large enterprise or cloud-based storage environment, storage teams are responsible for providing storage to many applications used by the business clients. Over time, applications may no longer need certain allocated storage volumes, or the applications and the servers they run on may be decommissioned entirely. Often there is imperfect communication between storage administrators and the teams responsible for the applications. This can result in situations where the failures to notify the storage team that volumes can be reclaimed result in the storage volumes being unused, but consuming storage resources due to their allocation. Many storage teams lack the time and resources to hunt down reclaimable storage throughout the enterprise. Even those storage teams who have the resources to devote to reclamation report that it is a lengthy focused effort that is only undertaken several times per year.
A common technique for finding storage volumes which are candidates for reclamation is to use a tool to run a report for “orphan” volumes. Orphan or orphaned volumes are volumes that do not have an owning system assigned. The orphan volumes can be detected by scanning for the presence of host mappings on the storage system. Some tools create reports by correlating the relationships between servers' logical volumes and the volumes on the storage system. Unfortunately, many reports have errors and omissions. Further, there are valid reasons why a storage volume without a host assignment should not be reclaimed. For example, if the volume is a replication target or being used as part of a solution that does not require an explicit host assignment, e.g., count key data (CKD). So the mere fact that a storage volume is an orphan volume is insufficient to indicate that it should be reclaimed in a storage maintenance operation. In addition, other storage volumes, besides orphan volumes, are potential reclamation candidates.
An alternative approach for identifying storage volumes for storage reclamation or other storage maintenance is to query for storage volumes that have had no or minimal input/output for a sustained period of time, e.g., two weeks. This approach has the disadvantage of identifying false positives, such as volumes that are only active on a monthly or quarterly basis when batch processing occurs.